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From Kai Wang <>
Subject Re: Keyspace and table/cf limits
Date Sat, 06 Dec 2014 21:15:14 GMT
On Sat, Dec 6, 2014 at 11:22 AM, Eric Stevens <> wrote:

> Based on recent conversations with Datastax engineers, the recommendation
> is definitely still to run a finite and reasonable set of column families.
> The best way I know of to support multitenancy is to include tenant id in
> all of your partition keys.
> On Fri Dec 05 2014 at 7:39:47 PM Kai Wang <> wrote:
>> On Fri, Dec 5, 2014 at 4:32 PM, Robert Coli <> wrote:
>>> On Wed, Dec 3, 2014 at 1:54 PM, Raj N <> wrote:
>>>> The question is more from a multi-tenancy point of view. We wanted to
>>>> see if we can have a keyspace per client. Each keyspace may have 50 column
>>>> families, but if we have 200 clients, that would be 10,000 column families.
>>>> Do you think that's reasonable to support? I know that key cache capacity
>>>> is reserved in heap still. Any plans to move it off-heap?
>>> That's an order of magnitude more CFs than I would want to try to
>>> operate.
>>> But then, I wouldn't want to operate Cassandra multi-tenant AT ALL, so
>>> grain of salt.
>>> =Rob
>> I don't know if it's still true but Jonathan Ellis wrote in an old post
>> saying there's a fixed overhead per cf. Here is the link.
>> Even if it's improved since C*
>> 1.0, I still don't feel comfortable to scale my system by creating CFs.
I agree with Eric on encoding tenant id into the partition key. It seems OP
wants to use keyspace to achieve client isolation. But I think multitenancy
is too high level as a feature to be put into the database layer. It's
better handled by the application IMO.

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